The present invention relates generally to the ability to access program, system information and system services within the Program and System Information Protocol (PSIP) and within a DTV Application Software Environment (DASE). More particularly, the present invention relates to enabling access to data that is not contained in declarative applications utilized within the PSIP and DASE environment. More particularly, still, the present invention enables HTML pages to perform active dynamic discovery of content and services within a digital multimedia broadcast environment.
The Advanced Television System's Committee (ATSC) has developed standards for use in the broadcast and the management of digital multimedia signals used for such applications as Digital Television (DTV) and High Definition Television (HDTV). The ATSC has established standards, such as S17, also know as DTV Application Software Environment (DASE). The DASE specification explicitly calls for co-existence of both procedural and declarative applications. Procedural applications are Xlets, which are the DTV extensions of applets. Declarative applications are XDML web-pages, which are DTV extensions of XDML pages, which are used to replace HTML pages previously used in DASE applications.
Current DASE standards utilize Application Program Interfaces (API) to enable procedural applications to access Program and System Information (PSI), which are typically handled by JavaTV API wrappers, and to use system services through the ATSC API's. In particular, the ATSC standardization effort emphasizes the DASE API as a necessary component that enables broadcaster applications to run on any receiver client, regardless of the specific underlying hardware and Operating System (OS), which achieves a write-once-run-anywhere paradigm.
Recent approaches, however, use declarative applications to perform functions previously performed by procedural applications. These declarative applications are useful in that they offer low development cost and high portability. DASE API, however, does not provide declarative applications means for PSI access. As a result, current declarative applications do not enjoy the services to which procedural applications have access. For example, there is a need for an API to access PSIP virtual channel tables for the purposes of generating an Electronic Program Guide (EPG).
Accordingly, what is needed is a declarative application or construction that provides access to DASE System services not previously available in the prior art.